My AC recently quit cooling. Fan runs, but now blows hot air. AC switch for cool is on and temp control is set to cool and AC fuse in cab is good.. I gauged the refrigerant lines and get a static pressure of about 110 PSI. Easy to turn compressor by hand, but clutch is not getting 12 volts. I checked both high and low pressure switches and both tested closed. Is there a relay I need to test or replace? If so where do I find it? Any guidance on a nextstep or a wiring schematic would be greatly appreciated. My VIN is TAW04913.
Check your messages.
I've got a video in this forum of same year and model with motor out that shows compressor wiring run + lineset routing as well.
I very much hoped to solve this problem without a second request, but find myself unexpectedly backed into a corner. From the schematic I drew a simplified diagram of the circuit that powers the AC compressor clutch. Troubleshooting led me to the temperature switch that is connected to a capillary tube in the evaporator coil. This switch tests open circuil and when I jump across it my AC compressor engages. I purchased a new switch (504-5979) from my CAT dealer, but it too tests open and does not allow my compressor clutch to engage. I am not accustomed to receiving defective OEM parts from CAT, is that a possibility here? If this switch is supposed to be normally open I do not understand how this circuit would work.
You've received a defective part.
The odds of this seemed slim. My problem caused by a failed switch and then a new in the box OEM replacement that tested the same. Oh well, first time for everything I guess. Thank you for the assistance. Back to my CAT dealer tomorrow.
could you please send me the 289d a/c schematic? Thanks
You'll have to supply a Serial Number to narrow it down. I see a dozen different different models of 289D.
taw03283
Simply jumping the two inline terminals will bypass that tstat.
Check your message inbox.
Inline terminals on the Tstat, that is. Black must be grounded. Conect the two at red together.